1. Field of the Invention
This invention relates to a method of obtaining increased conductivity in a material, and the increased conductivity material obtained thereby, suitable for use as a circuit element in a wide variety of electrical and electronic applications.
2. Description of the Prior Art
Conductors used in electrical and electronic applications often comprise a metallic element surrounded by a plastic or other organic insulating material. In the case of integrated circuits and other semiconductor devices, electrical conductors typically comprise metallic lines surrounded by an inorganic insulating material, for example silicon dioxide, or comprise heavily doped polysilicon material surrounded by more lightly doped silicon or silicon dioxide, etc. Recently, silicides--that is, silicon-metal compounds--have been increasingly used for obtaining reduced resistivities that aid in the performance of electronic circuits.
Most of the prior art conductors have comprised inorganic materials, as seen from the above examples. However, work has also been recently aimed at obtaining high conductivity materials from organic materials. For example, carbon-containing films have been pyrolized to produce films having a relatively high conductivity; see "Carbon Films With Relatively High Conductivity," by M. L. Kaplan et al, Applied Physics Letters, Vol. 36, pages 867-869 (1980). The resulting films were highly conductive, having a room temperature conductivity of about 250 (ohm-cm).sup.-1 ; that is, a resistivity of about 0.004 ohm-cm. They had either metallic or semiconducting behavior, depending on the preparation temperature.
It is typically desirable in electronic applications to obtain relatively fine-line conducting regions surrounded by an insulating region; for example, conductors that are used on circuit boards or to connect areas of integrated circuits. Therefore, a selective method of treating organic material to obtain high conductivity is desirable. Electron beams have been used to irradiate certain organic materials to obtain increased conductivity; see "Electron Beam Pattern Generation in Thin Film Organic Dianhydrides," by P. H. Schmidt et al, Applied Physics Letters, Vol. 40, pages 93-95 (1982). While the conductivity of the irradiated regions was substantially increased as compared to the nonirradiated regions, the highest conductivities obtained were only on the order of 1 (ohm-cm).sup.-1 for the material PTCDA. In numerous electrical and electronic applications, it is desirable or necessary to have substantially higher conductivity; that is, a resistivity substantially less than 1 ohm-cm.